The first talks came nearly a year ago, and ended in a draft agreement which the US embraced immediately, but moved slowly in debate in Iran. By the time Iran had decided to accept the deal, the US was rejecting it as “too late,” and stopped the deal.

The deal would have Iran sending a large portion of its uranium stockpile abroad to be enriched to 20 percent and turned into fuel rods for a medical reactor in Tehran, which produces isotopes for cancer treatment. Iran has been attempting to produce the 20 percent uranium itself, but says it will stop if they can complete a deal to secure a supply from abroad.